Heat spreaders are used to remove heat from structures such as an integrated circuit (IC). An IC die is often fabricated into a microelectronic device such as a processor. The increasing power consumption of processors results in tighter thermal budgets for a thermal solution design when the processor is employed in the field. Accordingly, a thermal interface solution is often needed to allow the die to reject heat more efficiently.
Various techniques have been employed to transfer heat away from a die. These techniques include passive and active configurations. One passive configuration involves a conductive material in thermal contact with the backside of a packaged die. This conductive material is often a heat pipe, heat sink, a slug, a heat spreader, or an integrated heat spreader (IHS). Adhesion of the IHS to the die is accomplished with a thermal interface material (TIM) such as a solder. The TIM adheres to the backside of the die and to the die-side of the IHS. Proper reflow of the TIM often is at temperatures in excess of 280° C. Because heating of the TIM also results in heating of the IHS and the IC die, subsequent cooling transfers significant compressive stresses to the die.
As die thicknesses grow smaller, the use of fluxes to protect the TIM composition during reflow, can hinder the adhesion of the TIM to the IHS and to the die backside. If not conducted properly, a flux-assisted TIM reflow can cause significant voids between the die and the IHS.